Daniel M. Kammen

Indoor air pollution from biomass combustion and acute respiratory infections in Kenya: an exposure-response study

BACKGROUND Acute respiratory infections (ARI) are the leading cause of the global burden of disease and have been causally linked with exposure to pollutants from domestic biomass fuels in less-developed countries. We used longitudinal health data coupled with detailed monitoring of personal exposure from more than 2 years of field measurements in rural Kenya to estimate the exposure-response relation for particulates smaller than 10 mm in diameter (PM(10)) generated from biomass combustion. METHODS 55 randomly-selected households (including 93 infants and children, 229 individuals between 5 and 49 years of age, and 23 aged 50 or older) in central Kenya were followed up for more than 2 years. Longitudinal data on ARI and acute lower respiratory infections (ALRI) were recorded at weekly clinical examinations. Exposure to PM(10) was monitored by measurement of PM(10) emission concentration and time-activity budgets. FINDINGS With the best estimate of the exposure-response relation, we found that ARI and ALRI are increasing concave functions of average daily exposure to PM(10), with the rate of increase declining for exposures above about 1000-2000 mg/m(3). After we had included high-intensity exposure episodes, sex was no longer a significant predictor of ARI and ALRI. INTERPRETATION The benefits of reduced exposure to PM(10) are larger for average exposure less than about 1000-2000 mg/m(3). Our findings have important consequences for international public-health policies, energy and combustion research, and technology transfer efforts that affect more than 2 billion people worldwide.

Effects of US Maize Ethanol on Global Land Use and Greenhouse Gas Emissions: Estimating Market-mediated Responses

Releases of greenhouse gases (GHG) from indirect land-use change triggered by crop-based biofuels have taken center stage in the debate over the role of biofuels in climate policy and energy security. This article analyzes these releases for maize ethanol produced in the United States. Factoring market-mediated responses and by-product use into our analysis reduces cropland conversion by 72% from the land used for the ethanol feedstock. Consequently, the associated GHG release estimated in our framework is 800 grams of carbon dioxide per megajoule (MJ); 27 grams per MJ per year, over 30 years of ethanol production, or roughly a quarter of the only other published estimate of releases attributable to changes in indirect land use. Nonetheless, 800 grams are enough to cancel out the benefits that corn ethanol has on global warming, thereby limiting its potential contribution in the context of Californias Low Carbon Fuel Standard.

Fixing a critical climate accounting error

Rules for applying the Kyoto Protocol and national cap-and-trade laws contain a major, but fixable, carbon accounting flaw in assessing bioenergy. The accounting now used for assessing compliance with carbon limits in the Kyoto Protocol and in climate legislation contains a far-reaching but fixable flaw that will severely undermine greenhouse gas reduction goals (1). It does not count CO2 emitted from tailpipes and smokestacks when bioenergy is being used, but it also does not count changes in emissions from land use when biomass for energy is harvested or grown. This accounting erroneously treats all bioenergy as carbon neutral regardless of the source of the biomass, which may cause large differences in net emissions. For example, the clearing of long-established forests to burn wood or to grow energy crops is counted as a 100% reduction in energy emissions despite causing large releases of carbon.

Quantifying Carbon Footprint Reduction Opportunities for U.S. Households and Communities

Carbon management is of increasing interest to individuals, households, and communities. In order to effectively assess and manage their climate impacts, individuals need information on the financial and greenhouse gas benefits of effective mitigation opportunities. We use consumption-based life cycle accounting techniques to quantify the carbon footprints of typical U.S. households in 28 cities for 6 household sizes and 12 income brackets. The model includes emissions embodied in transportation, energy, water, waste, food, goods, and services. We further quantify greenhouse gas and financial savings from 13 potential mitigation actions across all household types. The model suggests that the size and composition of carbon footprints vary dramatically between geographic regions and within regions based on basic demographic characteristics. Despite these differences, large cash-positive carbon footprint reductions are evident across all household types and locations; however, realizing this potential may require tailoring policies and programs to different population segments with very different carbon footprint profiles. The results of this model have been incorporated into an open access online carbon footprint management tool designed to enable behavior change at the household level through personalized feedback.

An innovation and policy agenda for commercially competitive plug-in hybrid electric vehicles

Plug-in hybrid electric vehicles (PHEVs) can use both grid-supplied electricity and liquid fuels. We show that under recent conditions, millions of PHEVs could have charged economically in California during both peak and off-peak hours even with modest gasoline prices and real-time electricity pricing. Special electricity rate tariffs already in place for electric vehicles could successfully render on-peak charging uneconomical and off-peak charging very attractive. However, unless battery prices fall by at least a factor of two, or gasoline prices double, the present value of fuel savings is smaller than the marginal vehicle costs, likely slowing PHEV market penetration in California. We also find that assumptions about how PHEVs are charged strongly influence the number of PHEVs that can be charged before the electric power system must be expanded. If most PHEVs are charged after the workday, and thus after the time of peak electricity demand, our forecasts suggest that several million PHEVs could be deployed in California without requiring new generation capacity, and we also find that the state’s PHEV fleet is unlikely to reach into the millions within the current electricity sector planning cycle. To ensure desirable outcomes, appropriate technologies and incentives for PHEV charging will be needed if PHEV adoption becomes mainstream.

Spatial Distribution of U.S. Household Carbon Footprints Reveals Suburbanization Undermines Greenhouse Gas Benefits of Urban Population Density

Which municipalities and locations within the United States contribute the most to household greenhouse gas emissions, and what is the effect of population density and suburbanization on emissions? Using national household surveys, we developed econometric models of demand for energy, transportation, food, goods, and services that were used to derive average household carbon footprints (HCF) for U.S. zip codes, cities, counties, and metropolitan areas. We find consistently lower HCF in urban core cities (∼ 40 tCO2e) and higher carbon footprints in outlying suburbs (∼ 50 tCO2e), with a range from ∼ 25 to >80 tCO2e in the 50 largest metropolitan areas. Population density exhibits a weak but positive correlation with HCF until a density threshold is met, after which range, mean, and standard deviation of HCF decline. While population density contributes to relatively low HCF in the central cities of large metropolitan areas, the more extensive suburbanization in these regions contributes to an overall net increase in HCF compared to smaller metropolitan areas. Suburbs alone account for ∼ 50% of total U.S. HCF. Differences in the size, composition, and location of household carbon footprints suggest the need for tailoring of greenhouse gas mitigation efforts to different populations.

Evidence of under-investment in energy R&D in the United States and the impact of Federal policy

Investments in energy technology research and development (R&D), and in associated human and institutional capacity, are fundamental to our ability to respond to changing economic and environmental needs. This paper uses data on R&D investments and patent records to examine the relationship between expenditures on R&D and innovation, with a particular focus on the energy sector. We observe that R&D spending and patents, both overall and in the energy sector, have been highly correlated over the past two decades in the US. In addition, we observe that the R&D intensity of the US energy sector is extremely low when compared to other sectors. We argue that the data illustrates the critical role of public policy, as evidenced by the impact of recent technology transfer related legislation on the total number and on the ownership of innovations resulting from federally sponsored R&D. We conclude that there has been a significant and sustained pattern of under-investment in the US energy sector, and that recent declines in energy R&D exacerbate this situation. Innovation for the US energy infrastructure is also a significant driver of the international energy economy. Thus, the spillover from US under-investment detracts from the global capacity to respond to emerging risks such as global warming.

The Energy-Poverty-Climate Nexus

Community-level carbon abatement curves highlight opportunities for increased access to clean, efficient energy for the poor. Close to two-thirds of the worlds poorest people live in rural areas (1). Eradication of rural poverty depends on increased access to goods, services, and information, targets detailed in the United Nations Millennium Development Goals. However, alleviating poverty is hindered by two interlinked phenomena: lack of access to improved energy services and worsening environmental shocks due to climate change. Mitigating climate change, increasing energy access, and alleviating rural poverty can all be complementary, their overlap defining an energy-poverty-climate nexus. We describe interventions in a rural Nicaraguan community to show that energy services can be provided in cost-effective manners, offering the potential to address aspects of rural poverty while also transitioning away from fossil fuel dependence.

Photovoltaic module quality in the Kenyan solar home systems market

As one of the largest unsubsidized markets for solar home systems (SHSs) in the world, Kenya represents a promising model for rural electrification based on private purchases of clean decentralized photovoltaic technologies. Small amorphous-silicon modules dominate the market and most brands provide high quality and affordable service. Product quality varies widely, however, and the public has limited capacity to distinguish among competing brands. This imposes direct hardships on households with the misfortune to purchase low-quality equipment, and it constrains sales as some customers refrain from purchasing solar equipment due to the associated performance uncertainty. This article analyzes market failure associated with photovoltaic module quality in the Kenyan SHS market and develops strategies to address the problemFemphasizing that similar quality problems may exist for other SHS components and in other markets. The principal conclusion is that domestic product testing with public disclosure represents an inexpensive low-risk strategy, but it may prove inadequate. Mandatory product quality standards based on international testing regimes (e.g. IEC standards), augmented with a basic domestic testing option, would provide stronger assurance, but the risks associated with this intervention suggest caution. An emerging multilateral SHS market support effort (PVMTI) should ensure quality for the credit-based sales it promotes in Kenya; however, the long-term impact of this approach is not yet clear and it is unlikely to address quality problems associated with the existing unsubsidized sales-based markets for SHSs. Finally, fee-for-service models would decisively address quality problems, but launching this model in the Kenyan market would likely require large subsidies. r 2002 Elsevier Science Ltd. All rights reserved.

Accounting for the water impacts of ethanol production

Biofuels account for 1‐2% of global transportation fuel and their share is projected to continue rising, with potentially serious consequences for water resources. However, current literature does not present sufficient spatial resolution to characterize this localized effect. We used a coupled agro-climatic and life cycle assessment model to estimate the water resource impacts of bioenergy expansion scenarios at a county-level resolution. The study focused on the case of California, with its range of agroecological conditions, water scarcity, and aggressive alternative fuel incentive policies. Life cycle water consumption for ethanol production in California is up to 1000 times that of gasoline due to a cultivation phase that consumes over 99% of life cycle water use for agricultural biofuels. This consumption varies by up to 60% among different feedstocks and by over 350% across regions in California. Rigorous policy analysis requires spatially resolved modeling of water resource impacts and careful consideration of the various metrics that might act to constrain technology and policy options.